/*
 * gleem -- OpenGL Extremely Easy-To-Use Manipulators.
 * Copyright (C) 1998-2003 Kenneth B. Russell (kbrussel@alum.mit.edu)
 *
 * Copying, distribution and use of this software in source and binary
 * forms, with or without modification, is permitted provided that the
 * following conditions are met:
 *
 * Distributions of source code must reproduce the copyright notice,
 * this list of conditions and the following disclaimer in the source
 * code header files; and Distributions of binary code must reproduce
 * the copyright notice, this list of conditions and the following
 * disclaimer in the documentation, Read me file, license file and/or
 * other materials provided with the software distribution.
 *
 * The names of Sun Microsystems, Inc. ("Sun") and/or the copyright
 * holder may not be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS," WITHOUT A WARRANTY OF ANY
 * KIND. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, NON-INTERFERENCE, ACCURACY OF
 * INFORMATIONAL CONTENT OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. THE
 * COPYRIGHT HOLDER, SUN AND SUN'S LICENSORS SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL THE
 * COPYRIGHT HOLDER, SUN OR SUN'S LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
 * CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
 * REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
 * INABILITY TO USE THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGES. YOU ACKNOWLEDGE THAT THIS SOFTWARE IS NOT
 * DESIGNED, LICENSED OR INTENDED FOR USE IN THE DESIGN, CONSTRUCTION,
 * OPERATION OR MAINTENANCE OF ANY NUCLEAR FACILITY. THE COPYRIGHT
 * HOLDER, SUN AND SUN'S LICENSORS DISCLAIM ANY EXPRESS OR IMPLIED
 * WARRANTY OF FITNESS FOR SUCH USES.
 */

package org.gephi.lib.gleem.linalg;

/**
 * Represents a line in 3D space.
 */

public class Line {
    private Vec3f point;
    /**
     * Normalized
     */
    private Vec3f direction;
    /**
     * For computing projections along line
     */
    private final Vec3f alongVec;

    /**
     * Default constructor initializes line to point (0, 0, 0) and
     * direction (1, 0, 0)
     */
    public Line() {
        point = new Vec3f(0, 0, 0);
        direction = new Vec3f(1, 0, 0);
        alongVec = new Vec3f();
        recalc();
    }

    /**
     * Line goes in direction <b>direction</b> through the point
     * <b>point</b>. <b>direction</b> does not need to be normalized but must
     * not be the zero vector.
     */
    public Line(Vec3f direction, Vec3f point) {
        direction = new Vec3f(direction);
        direction.normalize();
        point = new Vec3f(point);
        alongVec = new Vec3f();
        recalc();
    }

    /**
     * Direction is normalized internally, so <b>direction</b> is not
     * necessarily equal to <code>plane.setDirection(direction);
     * plane.getDirection();</code>
     */
    public Vec3f getDirection() {
        return direction;
    }

    /**
     * Setter does some work to maintain internal caches.
     * <b>direction</b> does not need to be normalized but must not be
     * the zero vector.
     */
    public void setDirection(Vec3f direction) {
        this.direction.set(direction);
        this.direction.normalize();
        recalc();
    }

    public Vec3f getPoint() {
        return point;
    }

    /**
     * Setter does some work to maintain internal caches.
     */
    public void setPoint(Vec3f point) {
        this.point.set(point);
        recalc();
    }

    /**
     * Project a point onto the line
     */
    public void projectPoint(Vec3f pt,
                             Vec3f projPt) {
        float dotp = direction.dot(pt);
        projPt.set(direction);
        projPt.scale(dotp);
        projPt.add(alongVec);
    }

    /**
     * Find closest point on this line to the given ray, specified by
     * start point and direction. If ray is parallel to this line,
     * returns false and closestPoint is not modified.
     */
    public boolean closestPointToRay(Vec3f rayStart,
                                     Vec3f rayDirection,
                                     Vec3f closestPoint) {
        // Line 1 is this one. Line 2 is the incoming one.
        Mat2f A = new Mat2f();
        A.set(0, 0, -direction.lengthSquared());
        A.set(1, 1, -rayDirection.lengthSquared());
        A.set(0, 1, direction.dot(rayDirection));
        A.set(1, 0, A.get(0, 1));
        if (Math.abs(A.determinant()) == 0.0f) {
            return false;
        }
        if (!A.invert()) {
            return false;
        }
        Vec2f b = new Vec2f();
        b.setX(point.dot(direction) - rayStart.dot(direction));
        b.setY(rayStart.dot(rayDirection) - point.dot(rayDirection));
        Vec2f x = new Vec2f();
        A.xformVec(b, x);
        if (x.y() < 0) {
            // Means that ray start is closest point to this line
            closestPoint.set(rayStart);
        } else {
            closestPoint.set(direction);
            closestPoint.scale(x.x());
            closestPoint.add(point);
        }
        return true;
    }

    //----------------------------------------------------------------------
    // Internals only below this point
    //

    private void recalc() {
        float denom = direction.lengthSquared();
        if (denom == 0.0f) {
            throw new RuntimeException("Line.recalc: ERROR: direction was the zero vector " +
                "(not allowed)");
        }
        alongVec.set(point.minus(direction.times(point.dot(direction))));
    }
}
